1. Technical Field
The present invention relates to a vibrating reed, a gyro sensor using the vibrating reed, and an electronic apparatus, a mobile unit, etc. in which the vibrating reed is incorporated.
2. Related Art
For example, as described in Patent Document 1 (JP-A-5-256723), vibrating reeds used for gyro sensors are commonly known. When angular velocity motion is applied to a drive vibrating arm, the vibration direction of the drive vibrating arm changes due to action of Coriolis force. A new force component is generated in a specific direction in response to the Coriolis force. The force component causes motion of a detection vibrating arm. Accordingly, an output signal in response to the force component is output from the detection vibrating arm. In the example described in Patent Document 1, the detection vibrating arm and the drive vibrating arm continuously form one vibrating arm.
The main body of the vibrating reed may be cut out from a raw material such as a piezoelectric material, for example. For cutting out, masks are placed on the front surface and the rear surface of the raw material. When misalignment occurs between the masks, the side surface of the drive vibrating arm is not orthogonal to the front surface and the rear surface, but tilted. When a processing error is caused in the sectional shape of the drive vibrating arm on this account, the drive vibrating arm can not vibrate within a specified hypothetical plane, but vibrates in a hypothetical plane tilted from the specified hypothetical plane. The so-called diagonal vibration is generated. The phenomenon is called vibration leakage, and the vibration leakage component is superimposed on the force component in the output signal of the detection vibrating arm. As a result, the S/N-ratio of the output signal is deteriorated. An angular velocity signal is output from the vibrating reed with no angular velocity motion input thereto. In Patent Document 2 (JP-A-2008-209215), a cut is formed in the vibrating arm for removing the vibration leakage component. The cut in the vibrating arm triggers reduction in mechanical strength of the vibrating reed. In addition, as the vibrating reed becomes smaller, the influence on the behavior of the vibrating reed by the shape accuracy of the cut increases and further improvement of processing accuracy is required. However, the improvement of processing accuracy is difficult.